Vocal hyperfunction is generally viewed as an underlying component in a majority of voice disorders. However, there is a paucity of hard data concerning: 1) specific physiologic and acoustic manifestations of vocal hyperfunction, and 2) the actual role of hyperfunction in the development and maintenance of voice disorders. Thus, the major goal of this project is to further develop and use quantitative measures of voice production to provide objective descriptions of conditions referred to as "vocal hyperfunction". This work will involve the use of non-invasive, indirect measures of glottal air flow, subglottal air pressure, relative vocal fold contact area (EGG), the acoustic signal and a number of derived parameters to study four groups of voice- disordered subjects and one group of normals. Subject groups are designed so that the nature of hyperfunction can be studied in dysphonias that exist: 1) in the absence of organic pathology and 2) in association with benign organic vocal pathology believed to result from abuse/misuse of the voice. Measures will be examined in relation to an encoded description of the pathophysiological status of the larynx from a laryngological exam, an encoded voice history, and the results of perceptual tests. Interpretation of results will be aided by the visualization of vocal fold vibration patterns in video-stroboscopic recordings and through the use of a simple vocal fold model. The experimental design for this project is based on a set of interrelated hypotheses which form a descriptive framework of vocal hyperfunction. The framework holds that there are different types and stages of hyperfunctionally-related voice disorders. Data analysis and interpretation will be related to this framework. The results are expected to provide new information about hyperfunctional voice production in terms of inter- relationships among the aerodynamic, physiological and acoustic properties of vocal fold vibration. Such information should lead to new insights concerning the role of hyperfunction in the development and maintenance of various voice disorders. The knowledge obtained and measures developed in this project should lead to future improvements in clinical methods used to diagnose and treat hyperfunctional voice disorders.